I'm looking at the M4, just because it's smaller. Now I'm in the process of searching for a case that will house both the Mini-ITX board and the PS (right now I have an external PS and I'd love to get it all in the case, if that's possible).

Size is mini-itx, same as d201gly2. The northbridge HSF is only 30mm high off the board (cf D945GCLF at 45mm) as is the passive CPU heatsink. That is slightly lower than your avergae ram, and so the low height cases are good to go. The procase cs 3688 im using fits fine and its only 65mm high.

The PSU is only 60W though and designed for epia. Might work at a pinch if you have little other 5V needs. Would be good if intels documentation actually specified the motherboards power draw per rail, rather than the vague "supply requirements" figures they use. I just looked at the docs for d201gly2 and it says

None of which makes any sense to me. But my test showed that even if it was drawing ALL 5V it was using 4Amps on the 5V rail at idle. And whats the point of the 12V power conenctor if the board isnt really using any significant 12V power. Thats atom for you i guess.

Surely those specs should have a baseline MoB use figure and one that allows for fans, USB etc.

. Would be good if intels documentation actually specified the motherboards power draw per rail, rather than the vague "supply requirements" figures they use.

Whereas D945GCLF2 says:

3.3V 0.5A
5V 7.75A
12 0.8A

None of which makes any sense to me. But my test showed that even if it was drawing ALL 5V it was using 4Amps on the 5V rail at idle. And whats the point of the 12V power conenctor if the board isnt really using any significant 12V power. Thats atom for you i guess.

Surely those specs should have a baseline MoB use figure and one that allows for fans, USB etc.

Could someone else confirm deny these findings 7.75A on the 5v rail means the M3 is outo the window (max 6A) if its 4 then just could get away with it.
looks like the M4 is going to have to be used